Trump, though, has dismissed the idea that Russia is trying to help him by leaking the emails, calling it a "joke."

Trump went on to spark controversy on Wednesday when he also said he hoped Russian hackers obtained Clinton's emails from her private server and shared them with the FBI. He said on Thursday that he was only "being sarcastic."

President Obama has also said it was "possible" that Russians are trying to interfere in the U.S. election by dumping the emails.

“I am basing this on what Mr. Trump himself has said,” the president said. “And I think that Trump's gotten pretty favorable coverage back in Russia.”

Russian officials have warned the U.S. before that accusations it is interfering in the 2016 election could hurt relations.